P1398 Misfire Adaptive Numerator at Limit

SYMPTOM
P-1398 MISFIRE ADAPTIVE NUMERATOR AT LIMIT

WHEN MONITORED
Under closed throttle decel. with A/C off, engine coolant temp above 75 deg, & more than 50 seconds after engine start. Speed at which decel. occurs must be sufficient for given gear range, eg, above 36 mph in 1st gear or above 65 mph in high gear.

SET CONDITION
One of the crankshaft position sensor target windows has more than 2.86% variance from the reference window.

POSSIBLE CAUSES
- Crankshaft position sensor defective
- Crankshaft position sensor not properly installed
- Crankshaft position connector observable defect
- Flexplate damaged